%% Copyright (c) 2018, Loïc Hoguin <essen@ninenines.eu>
%%
%% Permission to use, copy, modify, and/or distribute this software for any
%% purpose with or without fee is hereby granted, provided that the above
%% copyright notice and this permission notice appear in all copies.
%%
%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

-module(ranch_crc32c).

-export([crc32c/1]).
-export([crc32c/2]).

-define(CRC32C_TABLE, {
	16#00000000, 16#F26B8303, 16#E13B70F7, 16#1350F3F4,
	16#C79A971F, 16#35F1141C, 16#26A1E7E8, 16#D4CA64EB,
	16#8AD958CF, 16#78B2DBCC, 16#6BE22838, 16#9989AB3B,
	16#4D43CFD0, 16#BF284CD3, 16#AC78BF27, 16#5E133C24,
	16#105EC76F, 16#E235446C, 16#F165B798, 16#030E349B,
	16#D7C45070, 16#25AFD373, 16#36FF2087, 16#C494A384,
	16#9A879FA0, 16#68EC1CA3, 16#7BBCEF57, 16#89D76C54,
	16#5D1D08BF, 16#AF768BBC, 16#BC267848, 16#4E4DFB4B,
	16#20BD8EDE, 16#D2D60DDD, 16#C186FE29, 16#33ED7D2A,
	16#E72719C1, 16#154C9AC2, 16#061C6936, 16#F477EA35,
	16#AA64D611, 16#580F5512, 16#4B5FA6E6, 16#B93425E5,
	16#6DFE410E, 16#9F95C20D, 16#8CC531F9, 16#7EAEB2FA,
	16#30E349B1, 16#C288CAB2, 16#D1D83946, 16#23B3BA45,
	16#F779DEAE, 16#05125DAD, 16#1642AE59, 16#E4292D5A,
	16#BA3A117E, 16#4851927D, 16#5B016189, 16#A96AE28A,
	16#7DA08661, 16#8FCB0562, 16#9C9BF696, 16#6EF07595,
	16#417B1DBC, 16#B3109EBF, 16#A0406D4B, 16#522BEE48,
	16#86E18AA3, 16#748A09A0, 16#67DAFA54, 16#95B17957,
	16#CBA24573, 16#39C9C670, 16#2A993584, 16#D8F2B687,
	16#0C38D26C, 16#FE53516F, 16#ED03A29B, 16#1F682198,
	16#5125DAD3, 16#A34E59D0, 16#B01EAA24, 16#42752927,
	16#96BF4DCC, 16#64D4CECF, 16#77843D3B, 16#85EFBE38,
	16#DBFC821C, 16#2997011F, 16#3AC7F2EB, 16#C8AC71E8,
	16#1C661503, 16#EE0D9600, 16#FD5D65F4, 16#0F36E6F7,
	16#61C69362, 16#93AD1061, 16#80FDE395, 16#72966096,
	16#A65C047D, 16#5437877E, 16#4767748A, 16#B50CF789,
	16#EB1FCBAD, 16#197448AE, 16#0A24BB5A, 16#F84F3859,
	16#2C855CB2, 16#DEEEDFB1, 16#CDBE2C45, 16#3FD5AF46,
	16#7198540D, 16#83F3D70E, 16#90A324FA, 16#62C8A7F9,
	16#B602C312, 16#44694011, 16#5739B3E5, 16#A55230E6,
	16#FB410CC2, 16#092A8FC1, 16#1A7A7C35, 16#E811FF36,
	16#3CDB9BDD, 16#CEB018DE, 16#DDE0EB2A, 16#2F8B6829,
	16#82F63B78, 16#709DB87B, 16#63CD4B8F, 16#91A6C88C,
	16#456CAC67, 16#B7072F64, 16#A457DC90, 16#563C5F93,
	16#082F63B7, 16#FA44E0B4, 16#E9141340, 16#1B7F9043,
	16#CFB5F4A8, 16#3DDE77AB, 16#2E8E845F, 16#DCE5075C,
	16#92A8FC17, 16#60C37F14, 16#73938CE0, 16#81F80FE3,
	16#55326B08, 16#A759E80B, 16#B4091BFF, 16#466298FC,
	16#1871A4D8, 16#EA1A27DB, 16#F94AD42F, 16#0B21572C,
	16#DFEB33C7, 16#2D80B0C4, 16#3ED04330, 16#CCBBC033,
	16#A24BB5A6, 16#502036A5, 16#4370C551, 16#B11B4652,
	16#65D122B9, 16#97BAA1BA, 16#84EA524E, 16#7681D14D,
	16#2892ED69, 16#DAF96E6A, 16#C9A99D9E, 16#3BC21E9D,
	16#EF087A76, 16#1D63F975, 16#0E330A81, 16#FC588982,
	16#B21572C9, 16#407EF1CA, 16#532E023E, 16#A145813D,
	16#758FE5D6, 16#87E466D5, 16#94B49521, 16#66DF1622,
	16#38CC2A06, 16#CAA7A905, 16#D9F75AF1, 16#2B9CD9F2,
	16#FF56BD19, 16#0D3D3E1A, 16#1E6DCDEE, 16#EC064EED,
	16#C38D26C4, 16#31E6A5C7, 16#22B65633, 16#D0DDD530,
	16#0417B1DB, 16#F67C32D8, 16#E52CC12C, 16#1747422F,
	16#49547E0B, 16#BB3FFD08, 16#A86F0EFC, 16#5A048DFF,
	16#8ECEE914, 16#7CA56A17, 16#6FF599E3, 16#9D9E1AE0,
	16#D3D3E1AB, 16#21B862A8, 16#32E8915C, 16#C083125F,
	16#144976B4, 16#E622F5B7, 16#F5720643, 16#07198540,
	16#590AB964, 16#AB613A67, 16#B831C993, 16#4A5A4A90,
	16#9E902E7B, 16#6CFBAD78, 16#7FAB5E8C, 16#8DC0DD8F,
	16#E330A81A, 16#115B2B19, 16#020BD8ED, 16#F0605BEE,
	16#24AA3F05, 16#D6C1BC06, 16#C5914FF2, 16#37FACCF1,
	16#69E9F0D5, 16#9B8273D6, 16#88D28022, 16#7AB90321,
	16#AE7367CA, 16#5C18E4C9, 16#4F48173D, 16#BD23943E,
	16#F36E6F75, 16#0105EC76, 16#12551F82, 16#E03E9C81,
	16#34F4F86A, 16#C69F7B69, 16#D5CF889D, 16#27A40B9E,
	16#79B737BA, 16#8BDCB4B9, 16#988C474D, 16#6AE7C44E,
	16#BE2DA0A5, 16#4C4623A6, 16#5F16D052, 16#AD7D5351
}).

%% The interface mirrors erlang:crc32/1,2.
-spec crc32c(iodata()) -> non_neg_integer().
crc32c(Data) ->
	do_crc32c(16#ffffffff, iolist_to_binary(Data)).

-spec crc32c(CRC, iodata()) -> CRC when CRC::non_neg_integer().
crc32c(OldCrc, Data) ->
	do_crc32c(OldCrc bxor 16#ffffffff, iolist_to_binary(Data)).

do_crc32c(OldCrc, <<C, Rest/bits>>) ->
	do_crc32c((OldCrc bsr 8) bxor element(1 + ((OldCrc bxor C) band 16#ff), ?CRC32C_TABLE),
		Rest);
do_crc32c(OldCrc, <<>>) ->
	OldCrc bxor 16#ffffffff.

-ifdef(TEST).
crc32c_test_() ->
	Tests = [
		%% Tests from RFC3720 B.4.
		{<<0:32/unit:8>>, 16#8a9136aa},
		{iolist_to_binary([16#ff || _ <- lists:seq(1, 32)]), 16#62a8ab43},
		{iolist_to_binary([N || N <- lists:seq(0, 16#1f)]), 16#46dd794e},
		{iolist_to_binary([N || N <- lists:seq(16#1f, 0, -1)]), 16#113fdb5c},
		{<<16#01c00000:32, 0:32, 0:32, 0:32, 16#14000000:32, 16#00000400:32, 16#00000014:32,
			16#00000018:32, 16#28000000:32, 0:32, 16#02000000:32, 0:32>>, 16#d9963a56}
	],
	[{iolist_to_binary(io_lib:format("16#~8.16.0b", [R])),
		fun() -> R = crc32c(V) end} || {V, R} <- Tests].
-endif.
